Centromeres play an important role in segregating chromosomes into daughter cells, and centromeric DNA assembles specific proteins to form a complex referred to as the kinetochore. Among these proteins, centromere-specific histone H3 (CENH3) is one of the most characterized and found to be located only on active centromeres. We isolated four different CENH3-coding complementary DNAs (cDNAs), two from Nicotiana tabaccum and one each from the ancestral diploid species, Nicotiana sylvestris and Nicotiana tomentosiformis and raised an antibody against N-terminal amino acid sequences deduced from the cDNAs. Immunostaining with the antibody revealed the preferential centromere localization, indicating that the cDNAs cloned in this study encode authentic tobacco CENH3. A tobacco centromeric DNA sequence (Nt2-7) was also identified by chromatin immunoprecipitation cloning using the antibody.
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